ISBN 9783843910439

Zusammenfassung / Abstract

In this thesis we investigated radial metamaterials analytically and with computer simulations. The results are presented in eight publications in peer-reviewed journals that are included in this thesis and can be divided into three topics:

(i) Rolled-up metamaterials: In previous works in our group it was demonstrated that self-rolling strained metal-semiconductor layers can be used to produce metamaterials based on metal-semiconductor microtubes. In publication 1 we investigate the use of the walls of metal-semiconductor microtubes as broadband hyperlenses and demonstrate that the hyperlensing ability is not limited to the effective plasma frequency of the structure, but occurs over a broad frequency range. Publication 2 investigates the creation of a magnetic response in arrays of metal-semiconductor microtubes. It is found that, if the structure dimensions are appropriately chosen, a negative effective permeability at terahertz frequencies can be achieved. We show in publication 3 that by drilling an array of nanoholes into the wall of a metal-semiconductor tube, a fishnet structure with a negative refractive index at near-infrared frequencies can be obtained. Our rolling-up technique allows the fabrication of stacked semiconductor quantum wells that are sandwiched between plasmonic nanostructures. In publication 4 we investigate the influence of surface plasmon polaritons on the quantum-well gain and find a fano-type coupling that can provide a strong transmission enhancement.

(ii) Hybrid plasmon-photon modes: Surface plasmon polaritons usually suffer from rather low quality factors, limiting their use in potential applications. In publication 5 and 6 we propose and demonstrate the application of hollow metal cylinders and metal-coated dielectric bottle resonators as microresonators for surface plasmons. We show that such resonators support hybrid high-quality-factor plasmon-photon modes with a plasmon-type field enhancement at the metal-air surface of the structure. The quality factors of these modes are up to 1000. The combination of high quality factors and plasmon-type field concentration at the resonators surface makes our structures particularly interesting for sensing applications.

(iii) Metal-dielectric transformation-optics devices: In publication 7 we show that a metamaterial consisting of metal particles that are embedded in a dielectric host material can be used to fabricate transformation-optics devices such as an invisibility cloak or an optical black hole at visible frequencies. We demonstrate in publication 8 that a straightforwardly realizable metal-rod device can act as an invisibility cloak in the visible regime.